ENVIRONMENTAL DESIGN
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- ItemAN ASSESSMENT OF LIFT SYSTEM PERFORMANCE IN SELECTED HIGH RISE BUILDINGS IN ABUJA CITY(2021-06)The performance of lift systems in high rise buildings is essential for the efficiency of vertical transportation system. However, high rise buildings are often confronted with problems associated with lift system performance such as long waiting time, vibration, door operation, lighting and noise level in lift car during ride. This study assessed the performance of lift system in selected high rise building in Abuja city with the view to enhancing the efficiency of vertical transport system in buildings. The study measures performance parameters such as the Average Waiting Time (AWT), Transit Time (TRT), Time to Destination (TTD), lift car interior sound level, lift car illumination, door operation timing and sound, levelling accuracy and ride quality of lift systems. The study adopted field survey research design, encompassing measurements and a structured checklist for the collection of relevant data on 14 selected high rise buildings and 41 lift systems in the Central Business District (CBD) of Abuja city. Six tools were used to measure the performance parameters of the lift systems within the selected buildings. The performance parameters were evaluated against the standard performance requirements for an ideal lift system. Results from analysis showed that 85.7% of the selected buildings have lift systems with AWT above minimum standard requirement, 64.3% with unsatisfactory interior sound level and 71.4% with poor ride quality. Conversely, 71.4% of these buildings have lift systems with optimum illuminance and 100% with satisfactory lift door operation. Results from the inferential statistics showed significant differences (p<0.05) in the mean value of AWT, TRT, TTD, lift car interior sound level, and lift acceleration. Based on the findings, the selected buildings were considered to have lift systems performing below expected standard. Nonetheless, the study provided data for lift performance parameters for optimizing the service delivery of lift systems within high rise buildings in Nigeria.
- ItemASSESSMENT OF RESIDENTS’ PARTICIPATION IN OUTDOOR RECREATION IN NASSARAWA LOCAL GOVERNMENT AREA, KANO STATE-NIGERIA(2021-12)In spite of the paucity of reliable data on residents‟ participation in outdoor recreation in developing countries when compared to the developed ones, the fact that engaging in outdoor recreation is immensely beneficial cannot be dismissed.The study aimed at assessing the residents‟ participation in outdoor recreation in Nassarawa L.G.A. Kano State with a view to revealing pattern and making appropriate recommendations. The specific objectives are to identify outdoor recreation facilities, examine the socioeconomic characteristics of residents, examine the characteristics of outdoor recreation participation and evaluate the pattern of participation and constraints in Nassarawa L.G.A. Kano state. The data for the study were obtained primarily through field observation and administration of 400 copies of questionnaires. Cluster and systematic random samplingtechniques wereused to administer questionnaire to target respondents. Both descriptive and inferential statistics were used for the data analysis. The result shows that, Nassarawa Local Government, which is a small spatial entity in relationto metropolitan Kano,has 107numbers of outdoor recreational facilities. The residents participate more (88.1%) in outdoor recreation and mostly in the weekends.The common and popular activity participated among non-facility based recreation includes family and friend visits, jogging and walking for pleasure with participation rate exceeding 50%. Among the facility-based recreation activities, football and park visits were found to be dominant with 67.6% and 27.5%,respectively. Outdoor recreation participation in Nassarawa, Kano also follows the general and global pattern of recreational activity participation which assumed that participation diminishes as age advances. Participation tends to be significantly associated with level of education-with low level of participation among those with lower education, high participation among those with average education and low participation among those with higher degrees. The study ascertained that income level of the respondents is not associated with their ability to participate in outdoor recreation in the study area. The perception of outdoor recreation constraints is contextually specific rather than general. Among the 20 different perceived outdoor recreation constraints investigated, the study found „security and personal safety‟ (M=3.24) as the most perceived constraints which was ranked 1st. While, „having physical disability‟ (M=1.92) and „having household member with physical disability‟ (M=1.80) were the least perceived constraints ranked, 19th and 20th, respectively. Non-participants were more likely than participants to feel constrained in thirteen of twenty constraints. The study also established that the perception of constraints varies with age, genders as well as between participants and non-participants. The studystrongly recommendsthat recreation plan should be prepared and implemented, focusing on provision of a wide range of recreation activities and programs opportunities, targeting particularly older age and females. The study concludes that, provision and availability of facilities in a particular geographical setting is really important to participation in outdoor recreation. This is shown in the contrasting pattern observed in Nassarawa from the common position in the global south.
- ItemRELIABILITY ANALYSIS OF HIGH VOLTAGE POWER EQUIPMENT IN AJAOKUTA STEEL COMPANY LIMITED (ASCL)(2021)Reliability of power equipment in Ajaokuta Steel Company Limited (ASCL), Ajaokuta, Kogi State is as important as the company as a whole. The study presents the reliability analysis of critical Power Equipment in Ajaokuta Steel Company Limited (ASCL), using one of the distribution substation, 7DS (Engineering Shops & Auxiliaries including Housing Estates) as a case study, for the purpose of assessing how frequent the failure of power equipment were experienced within the period of January to December 2020. To achieve this, failure data of power equipment like 11kV, 630A Oil Circuit Breakers (OCB) of Incoming Feeder to the substation as well as Outgoing Feeder Cubicle 32 and Outgoing Feeder Cubicle 5, Earth Fault Relay PTN, Overcurrent Relay PT3, Current Cut-off Relay PT1, Pole Discrepancy Protection Relay (for Single Phasing Fault), Voltage Transformer, 3-phase, 11/0.415kV Sub Service Transformer, Current Transformers, Manual isolator on Outgoing Feeders, 110V DC Battery Unit and Rectifier Unit were calculated using Microsoft Excel software and analysed using Fault Tree Analysis method. The Reliability of the distribution substation was determined using exponential distribution model. A model was developed using the reliability block diagram (RBD) method. A 10-year prediction using the exponential distribution model and the RBD model was obtained and comparison between the models was carried out. The outages/unavailability records were obtained from the Logbook of MSDS 1 Control Room. The Case Study Substation, 7DS is an unmanned Distribution Substation under MSDS 1. As a result, all data regarding 7DS Substation were obtained from MSDS 1 Control Room. Results show that the outgoing feeder 32 (Township Feeder 1) has the highest annual outage time/unavailability, thus contributing most to the interruptions in the substation with a failure rate of 0.021474607 per hour and annual outage time of 0.9141 hour. Another major contributor to interruptions in the substation thereby affecting delivery of electricity to the customers was earth fault failures having a failure rate of 0.016765799 per hour and outage time of 0.5676 hour, followed by current cut-off failures 0.012860225 per hour and 0.42996 hour and the outgoing feeder 5 (Township feeder 2), 0.014417382 per hour and 0.38268 hour respectively. Sub-service transformers 1SST & 2SST, voltage transformers 1VT & 2VT as well as current transformer had the same failure rates of 0.000112007 per hour. The least contributor to interruption within the period under review was the sub-service transformer 1SST & 2SST with a value of 0.00000233348 hour. The reliability of the entire substation obtained using the exponential distribution model was 91.77%. Using reliability block diagram, the substation has a reliability of 95.22%. The reliability of the substation is low compared to the IEEE standard of 99.99% for distribution substation. Hence with the value calculated for this substation, the reliability is low. Comparing the result obtained with the available reliability benchmarks, it is obvious that the substation has performed poorly and needs to be improved upon to increase its reliability indices. Routine maintenance and right of way clearance on all outgoing feeders should be carried out to reduce the rate of earth fault and current cut off system tripping.
- ItemPROBABILISTIC-BASED SERVICE LIFE ANALYSIS OF REINFORCED CONCRETE COLUMNS SUBJECTED TO CORROSION DUE TO CARBONATION(2021)Reinforced concrete (RC) structures are subjected to several sources of uncertainties that highly Affects their response. These uncertainties are related to the structure geometry, material properties and the loads applied. The lack of knowledge on the potential load, as well as the uncertainties related to the structural features shows that the design of RC structures could be made in a reliability framework. Most of the infrastructural development in Nigeria are in concrete and the environmentally unsustainable emission of carbon dioxide by industries and commercial outfits expose these concrete structures to carbonation.The parameter for load and resistance of reinforced concrete structures are random in nature and the current limit state design criteria in codes for such structures are largely deterministic. Field and Numerical experimentation were used for the Analysis. Monte Carlo Simulation (MCS) method of structural reliability was used for the Service Life Reliability analysis of the reinforced concrete column subjected to corrosion due to carbonation and the results were used to develop failure modes using Microsoft Excel Framework. The Service life reliability analysis of the reinforced concrete columns was based on the stochastic models of the basic design variables as well as the deterministic variables. The used corrosion rates are 0.02mm/year, 0.04mm/year, 0.06mm/year, 0.08mm/year, 0.1mm/year and 0.12mm/year. It was clearly established that at corrosion rates of 0.06mm/year, the service life reliability of the column dropped to 50% after 40 years corrosion exposure from 90% at the onset of the corrosion (10 years after construction).
- ItemMODELING DURATION OF BUILDING RENOVATION PROJECTS(2021)Accurate estimation of construction time has been identified as a major problem to the construction industry at large, several efforts have being made to develop models to predict duration of construction projects, researchers argued that development of models to predict duration of renovation projects is in its preliminary stage and went on to develop a model to predict duration of renovation projects. Existing models are scope based model and researchers have questioned the accuracy of scope based models as they do not include other non-scope factors which affect duration of projects. This study is aimed at developing a model which incorporate both scope and non-scope factors in predicting duration of building renovation projects. To achieve this aim, non-scope factors as well as project scope factors with good predictive abilities were firstly, identified from literature. A questionnaire survey was then used to obtain from construction firms; basic data/information relating to the identified project scope factors as well as data/information relating to impact of the non-scope factors on duration of building renovation projects. Out of a computed sample size of 357 TETfund building renovation projects, data relating to 121 completed TETfund building renovation projects were provided by the construction firms. Descriptive statistics was used to gain an overview of data obtained from the questionnaire survey, the study revealed that the most significant factors that affect duration of building renovation projects are variations, incomplete scope of work, material delivery, scarcity of materials, labour productivity, and owner financial capacity are the top five factors that influence duration of renovation projects. inferential statistics was used to determine the variance in duration of different categories of renovation projects and the ANOVA shows that statistical significant difference exist in duration of different types of renovation projects. 90% of the data was used to develop an artificial neutral network models on SPSS25. MAPE and T-Test were used to validate the models. 8 Artificia Nuera Network models were developed one multilayer perceptron (MLP) and radial basis function (RBF) model for each category. The accuracy of the models are 86%, 80%, 90%, 87%, 91%, 87%, 98%, 96% in this other; MLP(General), RBF(General), MLP(Block of offices and classroom), RBF(Block of offices and classrooms), MLP(Library), RBF(Library), MLP(Theatre), RBF(Theatre). The developed models will help project managers to accurately predict the duration of building renovation projects.